Quantizer Design

1. A method for decoding video data, executable by a processor, comprising: receiving video data comprising one or more quantized coefficients; mapping one or more quantization index values associated with the quantized coefficients to one or more quantization step sizes based on a piecewise exponential mapping from a quantization index value to a corresponding quantization step size, wherein the piecewise exponential mapping comprises two or more portions applying different respective exponential mappings; and decoding the video data by performing an inverse quantization based on the one or more quantization step sizes.

2. The method of claim 1, wherein a first range associated with the one or more quantization index values is dependent on an internal bit-depth associated with the video data.

3. The method of claim 2, wherein the first range is larger for larger internal bit-depths.

4. The method of claim 1, wherein the exponential mapping is performed according to: quantization step=A*Bquantization index value/c.

5. The method of claim 4, wherein A, B, and C are constants for at least a subset of the one or more quantization index values.

6. The method of claim 4, wherein A, B, and C are constants for all of the one or more quantization index values.

7. The method of claim 4, wherein B is equal to 2.

8. The method of claim 4, wherein A is selected from the group consisting of: 4, 8, 16, 19, 24, and 32.

9. The method of claim 4, wherein C is a value corresponding to an upper bound of a range of the one or more quantization index values.

10. The method of claim 4, wherein C is a value in a range from 3 to 64.

11. The method of claim 1, wherein the video data further comprises one or more second quantized coefficients, and wherein one or more second quantization index values associated with the one or more second quantized coefficients are mapped to one or more second quantization step sizes based on a linear mapping.

12. The method of claim 11, wherein the linear mapping is performed according to: quantization step=X*quantization index value+Y.

13. The method of claim 12, wherein X is selected from the group consisting of: 1, 2, 4, and 8.

14. The method of claim 12, wherein Y is selected from the group consisting of: 4, 8, 16, and 32.

15. A method for encoding video data, executable by a processor, comprising: receiving video data; generating one or more coefficients from the video data; mapping one or more quantization index values associated with the coefficients to one or more quantization step sizes based on a piecewise exponential mapping from a quantization index value to a corresponding quantization step size, wherein the piecewise exponential mapping comprises two or more portions applying different respective exponential mappings; and encoding the video data by performing a quantization of the one or more coefficients based on the one or more quantization step sizes.

16. The method of claim 15, further comprising signaling the encoded video data in a video bitstream.

17. The method of claim 15, wherein a first range associated with the one or more quantization index values is dependent on an internal bit-depth associated with the video data.

18. The method of claim 15, further comprising generating one or more second coefficients, wherein one or more second quantization index values associated with the one or more second coefficients are mapped to one or more second quantization step sizes based on a non-exponential mapping.

19. A non-transitory computer-readable storage medium storing a video bitstream that is generated by a video encoding method, the method comprising: receiving video data; generating one or more coefficients from the video data; mapping one or more quantization index values associated with the coefficients to one or more quantization step sizes based on a piecewise exponential mapping from a quantization index value to a corresponding quantization step size, wherein the piecewise exponential mapping comprises two or more portions applying different respective exponential mappings; and encoding the video data by performing a quantization of the one or more coefficients based on the one or more quantization step sizes.

20. The non-transitory computer-readable storage medium of claim 19, wherein the video bitstream comprises the encoded video data that includes a set of quantized coefficients.